Method of and arrangement for regulating evaporators and like apparatus, particularly in connection with elastic fluid turbine plants



Sept. 25, 1934. D. F. WARNER 1,974,976

METHOD OF AND ARRANGEMENT FOR REGULATING EVAPORATORS AND LIKE APPARATUS,

PARTICULARLY IN CONNECTION WITH ELASTIC FLUID TURBINE PLANTS Filed Dec. 11. 1951 F'i I. 4

mg. a.

Y Invento'r": Donald F \A/QT'her",

His Attorney.

atented' Sept. 25, 1934 UNITED STATES PATENT; OFFICE METHOD OF AND ARRANGEMENT FOR REGULATING EVAPORATORS AND LIKE APPARATUS, PARTICULARLY IN CONNEC- TION PLANTS WITH ELASTIC FLUID TURBINE Donald F. Warner, Lynn, Mass., assignor to General Electric Company, a corporation of New Y rk fluid plants, although it is not necessarily limitedthereto.

There are cases in which the ordinary method of regulating the fluid supply to an evaporator or like apparatus involves certain dimculties in obtaining a stabilized process owing to the time lag between the initiation of a certain regulating actuation and the achievement of the desired result. If, for instance, the pressure or the temperature of a substance to be heated in an evaporator is too low, certain valve means may be opened in order to supply more heat energy to the evaporator. The opening actuation normally lasts until the desired result is obtained, that is, in the present instance, until a. predetermined temperature or pressure of the substance to be heated within the evaporator is reached. Owing to the comparatively long time between the initiation of a certain regulating actuation and the accomplishment of the desired result, over and under regulation of the apparatus may result.

The object of my invention is to provide an improved method of and arrangement for regulating such plants whereby over and under regu lation is substantially avoided.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto.

In the drawing Fig. 1 represents a diagrammatic illustration, partly in cross section, of an arrangement embodying my invention in combination with an elastic fluid turbine plant, and Fig. 2 shows a modification of a part of such an arrangement.

Referring to Fig. 1, 1 designates an evaporator having an inlet conduit 2 and an outlet conduit 3 and being supplied with exhaust steam through a conduit 4. connected to the exhaust of a back pressure turbine 5, the latter being shown by way of example as a prime mover for an electric generator 6 which supplies electric energy to a line 7 and has its frequency fixed by external means.

The evaporator, as shown in the present instance, may serve for evaporating water, for which purpose I have shown a water supply conduit 8 and a conduit 9 through which the generated steam is discharged. Connected to conduit 9 by means of a pipe 10 is a pressure responsive device 11, in the present instance shown as comprising a cylinder 12 and a bellows 13 within said cylinder and being connected to a stem 14. Provided on stem 14 is an adjustable spring 15 which normally presses the bellows in a downward direction. The desired steam pressure can be obtained by properly adjusting spring 15.

Connected to the exhaust elastic fluid supply conduit 4 by means of a pipe 16 is a pressure responsive device 1'7 comprising a cylinder 18 and a bellows 19 therein connected to a stem 20. These pressure responsive devices 11 and 18 form important parts of my arrangement.

The control mechanism of the steam turbine, as shown in the present instance, comprises an admission valve 21 through which steam or like elastic fluid is supplied to the turbine and in which a valve disk 22 is arranged connected to an operating lever 23, one end of which is provided with a roller 24 which rests on a cam 25. The latter has a surface 26 which may be termed the valve opening surface and is carried by a shaft 27 on which is mounted a pinion 28 which meshes with a rack 29 on the rod 30 of a fluid actuated motor 31. 32 indicates the piston of the fluid actuated motor, 33 the cylinder and 34 a pilot valve for controlling the motor. The latter has been shown by way of example as a double actuated hydraulic relay and its operation is as follows: If the pilot valve is moved upwardly, oil or like fluid is forced into the upper part of the cylinder 33 and drained ofi from the lower part thereof to the efiect that piston 32 is moved downwardly. The downward movement of piston 32 causes a corresponding downward movement of the pilot valve such that the latter resumes its original position; this being well known to those skilled in the art, is only briefly described. When piston 32 of the fluid actuated motor moves downwardly the cam 25 is turned in a direction to open admission valve 21.

The stem 35 of pilot valve 34 is connected to a floating lever 36, one end of which is pivotally connected to rod 30 and the other end of which is connected by a link 3'? to the free end of a governor lever 38, an intermediate point of which is connected to a suitable speed governor 33a, in the present instance shownas one of the flyball type driven by suitable gears 38b from the turbine shaft 380. The other end of lever 38 is connected to a synchonizing arrangement, in the present instance indicated as comprising a motor 39, gears 40 and adouble threaded nut 41 provided on screw threaded rods 42 and 43, of which the latter is pivotally connected to the left end of governor lever 38. During operation of motor 39, nut 41 is rotated to cause bolt 43 to move in either direction. At constant speed of the turbine this movement causes lever 38 to turn about its pivotal connection with the speed governor, whereby the right-hand end or lever 38 eflfects through the lever mechanism and the hydraulic motor, adjustment of the admission valve for the turbine. With the synchronizing arrangement this valve can be set to cause the turbine to carry diflferent loads at constant speed. In order to permit proper actuation of the valve mechanism through pressure responsive devices 11 and 17, floating lever 36 is preferably made of two arms 47 and 48 which are pivoted to each other and are yieldably connected together by a spring 49. The speed governor is connected to-the upper arm 47 and the pilot valve stem 35 is connected to the lower arm 48. As long as floating lever 36 is free to move, arms 4'7 and 48 move together as a unit, as far as the regulation by the speed governor is concerned, whereby arm 48 is moved through the intermediary of spring 49.

The actuation of the turbine regulating mechanism by the pressure responsive devices 11 and 18 is accomplished by means of the following arrangement: Steam 14 of the pressure responsive device 11 is connected to a floating lever 51 of a fluid actuated motor 52 which comprises a cylinder 53, a piston 54 therein normally pressed downward by a spring 55 and being connected to the right hand end oi! lever 51, and a pilot valve 56 the disks of which are secured to a stem 57 which is pivoted to an intermediate point of lever 51. 58 is a stem to which piston 54 is fastened and which is connected to the right end of lever 51 and the left end of lever 59. The latter is fulcrumed at 60 and has its right end slidably arranged with the stem 20 of the pressure responsive device 18. Bearing against the end of lever 59 and surrounding stem 20 of the pressure responsive device 1'! is a tensioned loading spring 61. The motion of the hydraulic piston stem 58 in response to an actuation by the pressure responsive device 11 causes an upward or downward movement of the right end or fulcrumed lever 59 and thereby changes the tension of spring 61. The upper end of stem 20 of the pressure responsive device 18 is connected to a lever 62 fulcrumed at 63 and having its right end slidably arranged with respect to stem 50. The lower end of the latter has an abutment 64 so that a downward movement of the right-hand end of the fulcrumed lever 62 causes an actuation of the pilot valve 34 which eflects upward movement of piston 32- and closing of the admission valve 22.

The operation 01 my mechanism, as shown in Fig. 1, is as follows: The speed of the turbine is normally flxed by external means. Let us now assume the mechanism, in particular the evaporating process, be in a balanced condition which means that the exhaust fluid supplied to the evaporator is suflicient to evaporate a certain amount of water or the like and to cause a predetermined pressure of the steam passing through conduit 9. If now, for instance, the pressure in conduit 9 decreases owing to an increase in demand for evaporated steam, it will cause an expanding actuation of the bellows 13 of the pressure responsive device 11 to the efiect that the latter causes a downward movement of stem 14 and an actuation of the pilot valve 56. The pilot valve stem thereby is moved downward and permits oil to be supplied to the lower part of cylinder 53 to the effect that piston stem 54 moves upward. This upward movement causes a corresponding movement of the pilot valve whereby the latter resumes its original position. Upward movement of piston 54 also efiects a downward movement of the right end of lever 59 whereby the tension of the loading spring 61 is increased. The increased tension of loading spring 61 causes a downward movement oi! stem 20 of pressureresponsive device 18 and a corresponding upward movement of the right end of lever 62 to the effect that rod 50 is moved in an upward direction by the action of the yielding spring 49. The pilot valve stem 35 then opens the pilot valve ports to cause oil or like liquid to'be supplied to the upper part 01 cylinder 33 and to be drained oil from the lower part thereof. This eflects a downward movement of the piston 32 and a corresponding movement of lever 36 whereby the original position of the pilot valve 34 is resumed. The downward movement of piston 32 also causes a counter-clockwise movement of cam 25 to open the admission valve 22. The opening of the admission valve permits an increased amount of elastic fluid to be supplied to the turbine and accordingly a rising of pressure in the exhaust conduit 4. This increased pressure again causes the bellows of the pressure responsive device 18 to collapse and to effect an upward movement of stem 20. The further actuation of the mechanism through pressure responsive device 11 is thereby limited. It will readily be understood that the regulating actuation in the present instance is initiated by the pressure responsive device 11 connected to the supply line 9 and that this actuation continues until a certain increase in pressure in exhaust conduit 4 is reached, whereupon this increase of pressure causes actuation of the second pressure responsive device 18 which affects the loading spring 61 in the opposite sense to the eflect that further actuation by the pressure responsive device 11 is compensated and the operating process is stabilized.

It will be noted that floating lever 36 is designed so that the speed governor 38a may close the admission valve 22 ot the turbine even though the fluid actuated motor 52 may be actuated to open it. The speed governor in all cases acts as a preemergency governor, that is, the speed governor causes closing of the turbine admission valve whenever the speed of the turbine increases beyond a. predetermined value. Under ordinary conditions the speed governor is set to cause closing of the admission valve at a speed in the order of about 10% above normal speed. During normal operation the turbine load is not aifected by slight changes in speed due to changes in demand for load in the electric line, these load changes being transferred to other prime mover sets working in parallel with turbine 5. This is important in case the connection of the generator with line 7 is broken. It will also be noted that the upward movement of the right end of lever 62 only causes movement of fluid actuated motor 31 if the two parts 47 and 48 of the floating lever 36 are out of engagement. Similarly a downward movement 01' the right end of lever 62 only causes immediate actuation of the fluid actuated motor 31 if the end of this lever is in engagement with the abutment 64 of stem 50.

An increase of pressure in supply line 9 causes a collapsing actuation of bellows 13 of pressure responsive device 11 to the effect that stem 14 is moved upward against the pressure of spring 15 and causes an operation of fluid actuated motor 52 to the effect that the stem 58 is moved downd and the rightend o! lever 59 is moved upw ard thereby relieving the tension of loading 'spring 61. This effects a downward actuation of the right end. of fulcrumed lever 62 so that fluid actuated motor 31 is operated in a direction to cause closing of admission valve 22. The decreased flow of fluid to the turbine which thereby results effects a decrease of exhaust pressure. As soon as the pressure in the exhaust conduit 4 has reached a certain value it will effect actuation of pressure responsive device 18 to prevent further actuation of lever 59 on loading spring 61.

Referring to Fig. 2, in which I have shown a modification of my mechanism, according to which the supply of fluid to the heater or evaporator is regulated in response to temperature conditions of evaporated liquid, '70 indicates a heater or evaporator which is provided with an admission valve '71 through which a heating fluid may be passed to the evaporator, and an outlet '72 for the heating fluid. '73 represents a conduit for supplying water or like substance to be heated or evaporated and to be supplied to a plant, not shown in the drawing, through a conduit '74. The admission valve '71 may be connected to the exhaust of a turbine or to any other steam or heat supplying source. '75 represents a conduit having a restriction and being connected to a pressure responsive device '77. An actuating fluid, preferably a liquid, is supplied under substantially constant pressure through orifice '75. '76 designates an adjustable valve for adjusting the sensitivity of the apparatus. The pressure responsive device '77 comprises a cylinder '78 and a bellows '79 connected to a stem and normally pressed downward by an adjustable spring 81. Stem 80 is connected to the left end of a lever 82 which is fulcrumed at 83 and the right end of which is pivoted to a stem 84 carrying the valve disk 85 of regulating valve '71. 86 and 8'7 are branch conduits of conduit 75 in which are suitable valve means 88 and 89 actuated by temperature and pressure responsive means 90 and 91 respectively in terms of temperature conditions in the fluid supply conduit '74 and the fluid pressure in conduit 92 respectively. The temperature responsive device 90 comprises a cylinder 93 and a bellows 94 connected to stem 95 of valve means 88. Surrounding the stem 95 is a spring 96 provided within the casing to resist closing movement of valve 88. Connected to the upper part of the bellows is a tube 9'7, the right end of which extends into the supply conduit '74 and is properly sealed and filled with a fluid. If the temperature in conduit '74 increases it will cause expansion of the fluid within conduit 9'7 and thus an increased pressure within the bellows 94 to the effect that the latter expands and causes closing movement of valve means 88. The pressure responsive device 91 is similarly constructed and comprises a casing 98 in which is provided a diaphragm 99 connected to the piston stem 100 of valve means 89. 101 is a spring which resists closing actuation of valve means 89. The upper part of the casing 98 is connected to one end of a tube 102, the other open F end of which is connected to the supply conduit 92. An increase of pressure in conduit 92 causes an increase of pressure in the upper part of casing 98 to the efiect that diaphragm 99 moves downward and causes closing movement of valve means 39.

The operation of this mechanism is as follows: Assume the apparatus as shown is in balanced condition. If now for any reason the temperature of fluid generated in the evaporator and discharged through conduit '74 decreases, it will cause an actuation of the temperature responsive device 90 to open valve means 88 to the effect that more liquid supplied to conduit '75 is displaced through branch conduit 86 so that the pressure in conduit '75 and accordingly in the pressure responsive device decreases and allows expanding actuation of bellows '79. This effects a downward movement of stem 80 secured to the bellows 79 and a corresponding movement of the left end of lever 82 resulting in an upward movement of the right end thereof and an opening actuation of admission valve 85. The opening of valve 85 permits an increased rate of flow of fluid supplied to the evaporator. the evaporator causes an increase of pressure in :conduit 102 and the upper part of casing 98 which thereby causes partial closingof valve 89. The method with this arrangement comprises regulating of the pressure in conduit 92 in terms of temperature changes of the fluid delivered through conduit 74. It will readily be seen that the fluid pressure in conduit 92 is increased in terms of decrease of temperature in conduit '74. In this manner the temperature of fluid delivered through conduit '74 is maintained constant.

If the temperature in supply conduit '74 increases, an actuation of the different means in an opposite sense will take place, that is, temperature responsive device 90 will actuate valve means 88 to close, resulting in a decreased flow of fluid through branch conduit 86 and an increase of pressure in pressure responsive device '77. This causes collapsing actuation of bellows '79 and an upward movement of stem 80 to the effect that admission valve 85 is closed. As soon as the rate of flow within conduit 92 decreases it will affect pressure responsive device 91 to cause opening movement of valve means 89 so that further closing actuation of valve means 88 is compensated by corresponding opening actuation of valve means 89.

In accordance with the provisions of the patent statutes I have described the method of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

This increase in flow of fluid to What I claim as new and desire to secure by Letters Patent of the United States is:-

1. The combination with an evaporator, of a conduit for supplying a fluid to said evaporator, a valve means provided in said conduit for regulating the admission of fluid, another conduit for supplying a substance to be evaporated within said evaporator whereby heat energy of said fluid is transferred to said substance, a conduit for discharging generated vapor, a temperature responsive means for actuating said fluid admission controlling means in terms of temperature existing in said vapor discharging conduit, a pressure responsive means for compensating further valve actuation by said temperature responsive means in response to changed conditions in said fluid supply means caused by said temperature responsive means.

2. The combination with an evaporator, of a conduit for supplying a fluid to said evaporator,

a valve means in said conduit for regulating the admission of fluid, another conduit for discharging the vapor of a substance evaporated in said evaporator, a pressure responsive means for actuating the valve comprising a bellows, a conduit to which an actuating fluid is supplied under substantially constant pressure, two branch conduits connected to said conduit, a valve means in each of the branch conduits whereby actuating fluid may be displaced through the branch conduits, temperature and pressure responsive devices for actuating the valve means in said branch conduits, one of said devices being subjected to temperature conditions existing in the vapor discharge conduit of the evaporator and the other being subjected to the pressure existing in the fluid supply conduit for the evaporator.

3. The combination with an elastic fluid turbine comprising valve means for regulating the admission of fluid to said turbine and speed regulating means for actuating said valve means in response to load changes, of an evaporator having a conduit connected to the exhaust of the turbine whereby exhaust fluid is supplied to said evaporator and heat energy of this fluid is transferred to a substance within the evaporator, another conduit connected to said evaporator for discharging evaporated substance, pressure responsive means for controlling the supply of fluid to said turbine in terms of pressure of evaporated substance, and another pressure responsive device having a conduit connected to the fluid supply conduit of the evaporator for stabilizing fluid admission controlling actuation caused by said first pressure responsive device in terms of changed pressure conditions in said fluid supply conduit.

4;. The combination with an elastic fluid turbine comprising a valve for regulating the admission of elastic fluid to the turbine, of an evaporator having a conduit connected to the exhaust of the turbine whereby exhaust fluid is supplied to said evaporator and heat energy of this fluid is transferred to a substance within the evaporator, another conduit connected to the evaporator for discharging evaporated substance, means for operating the admission valve in response to a condition of evaporated substance, and another means for compensating the regulating action of the first named means in response to a condition of the exhaust fluid.

5. The combination with an evaporator, of a supply conduit for conducting a fluid to the evaporator, a discharge conduit for discharging an evaporated substance from the evaporator, means including a device connected to the discharge conduit for controlling the flow in the supply conduit in response to a condition of the discharged evaporated substance, and other means including a device connected to the supply conduit for compensating the action of the first named means in response to a condition of the fluid in the supply conduit.

6. The combination with an evaporator, of a supply conduit for conducting a fluid to the evaporator, a discharge conduit for discharging an evaporated substance from the evaporator, valve means for controlling the flow of fluid through the supply conduit, means including a pressure responsive device connected to the discharge conduit for positioning the valve means, and another pressure responsive device connected to the supply conduit for compensating the action of the first named pressure responsive device in response to pressure changes in the supply conduit.

DONALD F. WARNER. 

